how to get values from gridview in .net,c#

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C#

.NET

i am using this below code for checking product whether it is available or not but i am getting error as soon as i click on check availability button...the error is as follows

Specified argument was out of the range of valid values.
Parameter name: index

I am using the below code:

protected void chckdavail_Click(object sender, EventArgs e)
    {
        foreach (GridViewRow gvr in show_moreDetails.Rows)
        {

            int data1 = Convert.ToInt32(gvr.Cells[7].Text);
            int data2 = Convert.ToInt32(gvr.Cells[8].Text);
            int data3 = Convert.ToInt32(gvr.Cells[9].Text);
            int data4 = Convert.ToInt32(gvr.Cells[10].Text);

            ClsPDF obj1 = new ClsPDF();
            int returnstatus = 0;
            returnstatus = Convert.ToInt32(obj1.productcheck(10, data3, data1, data2,data4));
            if (returnstatus == 1)
            {
                lbldavail.Visible = true;
                lbldavail.Text = "Available";
                lbldavail.ForeColor = System.Drawing.Color.Red;

            }
            else if (returnstatus == 2)
            {
                lbldavail.Text = "Not Available";
                lbldavail.ForeColor = System.Drawing.Color.Green;
                lbldavail.Visible = true;
            }
        }

    }